1. Field of the Invention (Technical Field)
The present invention relates to a projectile comprising metastable intermolecular composite materials and use of such projectiles to combat a conflagration.
2. Description of Related Art
Explosives are energetic materials that typically include an oxidant and a reductant that react rapidly with each other to produce product gases (e.g., CO2, H2O, and others) and energy in the form of heat and shock. Explosives such as TNT, TATB, RDX, and nitroglycerine produce energy at a very fast and uncontrolled rate. For applications that require a more controlled rate of energy production, “Metastable Intermolecular Composite” (MIC) materials, also known in the art as “Metastable Interstitial Composite” materials, have been developed.
MIC materials have been described, for example, in U.S. Pat. No. 5,266,132 to W. C. Danen et al. entitled “Energetic Composites,” and in U.S. Pat. No. 5,606,146 to W. C. Danen et al. entitled “Energetic Composites and Method of Providing Chemical Energy,” both hereby incorporated by reference. The MIC materials described in the '132 and '146 patents are layered materials that include alternating layers of oxidant and reductant. The oxidant layers are physically separated from the reductant layers by buffer layers. When the buffer layers are disrupted, the oxidant and reductant layers come into contact and react to produce chemical energy. The amount of energy produced and the rate of energy production depend on, among other things, the chemical composition of the oxidant and reductant layers and the number and thickness of these layers.
MIC materials in the form of powders are also known (see U.S. Pat. No. 5,717,159 to G. Dixon et al. entitled “Lead-Free Percussion Primer Mixes Based on Metastable Interstitial Composite (MIC) Technology,” and U.S. Pat. No. 6,666,936 to B. Jorgensen et al. entitled “Energetic Powder,” both hereby incorporated by reference. The MIC powders of the '159 patent are a blend of oxidant powder and reductant powder. The powders are used as percussion primers. The reductant powder is aluminum powder made up of aluminum particles having a thin oxide coating. One percussion primer composition is a mixture of about 45 weight percent of reductant aluminum powder and about 55 weight percent of oxidant molybdenum trioxide powder. Another primer composition is a mixture of about 50 wt % aluminum powder and about 50 wt % polytetrafluoroethylene.
Metastable Intermolecular Composite materials differ from more conventional composite materials in that the individual reductant particle sizes of MIC materials are on the nanoscale (10−9 meter) instead of millimeter or sub-millimeter scale (10−4 meter to 10−5 meter). These changes in the particle size result in significant changes in the chemical and mechanical properties of the powder mixture. The burn rate observed for MIC powder composed of these smaller sized powder reductant particles is much higher than for powder composed of larger reductant particles. Instead of burning at tens of millimeters per second, for example, MIC materials are capable of combustion velocities of tens of meters per second up to kilometers per second. The physical properties of the particles, such as melting points, can also change drastically.
Spot fires are used to change the course of large forest fires and other wildfires, but in order for the main fire to be drawn to the spot fire, the smaller fire must be hotter. This is because the higher temperature creates a larger oxygen consumption, which in turn creates the draft that draws the main fire to the spot fire. Stronger drafts make the spot fires more effective.
Currently, spot fires are started by dispensing small balls, approximately the size of ping-pong balls, filled with an anti-freeze/permanganate solution. However, the balls often jam in the dispenser, thus creating a hazard on the dispensing aircraft. Consequently, firefighters need a safer and more effective means to start spot fires. Gelled gasoline is sometimes used for this purpose, which again has problems with safe transport and deployment.
The present invention provides a spot fire accelerant system and projectile that is safer, hotter, and can be made compatible with existing aircraft. A MIC material is preferably used as the basis for the spot fire starter. These are solid and very stable and when ignited release significantly more heat than antifreeze/permanganate solutions. MICs can be easily packaged in many different configurations.
Because MIC materials are so stable and insensitive, they can be transported safely. In addition, if a ball containing MICs jams in the dispenser, it will not ignite and can be removed without danger.